Data modified when passing to C from Ruby using NUM2LL and NUM2INT -


i have c module testing ruby test extending ruby piece of c code. number above 2 ** 24 -1 being modified. need pass 64-bit values , forth between ruby , c , should bit-precise. thoughts appreciated.

in c extension: long int sig_val; sig_val = num2ll(sig) // sig type value , ruby number passed on c

. . . few example of data passed:

  • (2^34 -1) * 16 ==> c receives (2^34) * 16
  • (2^34 +1) * 16 ==> c receives (2^34) * 16
  • (2^24 +1) * 16 ==> c receives (2^24) * 16
  • (2^25 -1) ==> c receives (2^25)
  • (2^24 -1) ==> c receives (2^24 -1) (correct)

any number below correct.

thank you!

copying answer comments in order remove question "unanswered" filter:

i realized in code, there typecast float causes ruby limit number of bits 24 (as per single point ieee754 guess). can pass 64-bit wide numbers using num2ll , ll2num. thank you

~ answer per aalavi


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